The BiG Stink: Organic vs. Conventional, Round 3 – Energy Use

Welcome back to the BiG Stink and thanks for joining me for Round 3 of the great conventional vs. organic farming inquisition! Here’s a rapid recap: So far in this debate I, your trusty guide Faith, have defined organic and conventional agriculture; explored the impacts of both methods on soil health; and examined the ins and outs of land use efficiency. Today’s agenda? Diving into emissions and energy inputs for conventional and organic farming.

For my purposes, energy inputs for crop production are fossil fuels needed for equipment and transport of materials, fertilizer, pesticides, and herbicides. The largest energy sucker for organic farming was diesel fuel. Diesel fuel is needed to keep on-site machinery rolling and to bring in supplies such as seeds and natural soil amendments like compost and fertilizers like manure.

When assessing conventional agriculture, though, diesel fuel use was in the number two slot. The single largest energy sink in modern agriculture was the production and distribution of nitrogen fertilizers. To let that soak in, consider that the production and distribution of one ton of synthetic fertilizer was estimated to consume the equivalent of one and a half tons of gasoline! One study found that nitrogen fertilizer accounted for a whopping 41% of total energy input. Compared to fertilizer, pesticides and herbicides were miniscule, accounting for a measly 10% of inputs for conventional farming. Though it varied from study to study, organic agriculture inputs overall were found to be 28-32% less than those of conventional methods.

Much like inputs, greenhouse gas emissions were dominated by nitrogen. The single largest contributor to emissions in conventional and organic farming was nitrous oxide (N20). Both methods spew a fair amount of the potent greenhouse gas during farming. Agriculture (be it conventional or organic) is the largest source of N20 and accounts for 79% of U.S. emissions of nitrous oxide. Where is all this nitrogen coming from? As mentioned while dissecting inputs, conventional farming relies heavily on synthetic fertilizers and nitrous oxide is a byproduct created during the manufacture of the synthetic fertilizers.

What about organic agriculture? Since most synthetic nitrogen fertilizers are off limits for organic methods, farmers rely upon the use of compost and manure for nitrogen. N20 is a naturally occurring compound and a normal byproduct of the nitrogen cycle. Nitrous oxide is emitted when microbes break down the various forms of nitrogen (nitrate, nitrite, nitrogen dioxide – I’ll stop now) found in manure and compost.

Naturally occurring or not, organic and conventional agriculture have the same major greenhouse gas emitter, N20. That does not mean the farming methods have the same overall emissions! According to the Rodale Farming Systems Trial (FST), conventional agriculture oozes out nearly 40% more greenhouse gas emissions per pound of crop, largely owing to the manufacture, production,and application of synthetic fertilizers.

Interestingly, in my previous post on land use I pointed out that conventional agriculture puts out more crop per acre. However, now I know organic farms were superior energy misers than their conventional counterparts and were found to require nearly a thirdless energy inputs. The “organic advantage” means greater crop output relative to energy inputs and fewer emissions per pound of crop. Or in other words: more bang per energy buck. And less gassy.
And so with that, we’re three quarters of the way through this series and the end is nigh! Please stay tuned, keep your eyes peeled, and keep an ear out for the final round of the conventional vs. organic debate, where we’ll explore the uplifting subject of chemical and pesticide leaching.